The present invention is directed to a MOSFET on a SOI substrate.
In MOSFETs on extremely thin surface layers such as, for example, given employment of SOI substrates with an extremely thin useful layer of silicon (what is referred to as a silicon body layer) for the manufacture of fully depleted MOSFETs, the cutoff voltage is highly dependent on the thickness of the silicon body, this being very difficult to technologically govern. Although the cutoff voltage is kept within narrow limits given employment of thicker layers, the kink effect occurs, this producing a shift of the substrate potential due to substrate current that does not flow off, given an increasing, applied voltage and that can only be avoided by a terminal contact at the silicon body layer via which the substrate current can then be diverted. Fully depleted and partially depleted MOSFETs on an SOI substrate have been realized with a body terminal (for example, E. P. Ver Ploeg et al. in IEDM 92, 337 through 340 (1992)). The recited solutions, however, are usually not compatible without further ado with the overall process and require additional technological techniques, or lead to an asymmetry of the MOSFETs that is disadvantageous for circuit applications.